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A081210 In prime factorization of n replace each prime power p^e with the greatest squarefree number <= p^e. 6
1, 2, 3, 3, 5, 6, 7, 7, 7, 10, 11, 9, 13, 14, 15, 15, 17, 14, 19, 15, 21, 22, 23, 21, 23, 26, 26, 21, 29, 30, 31, 31, 33, 34, 35, 21, 37, 38, 39, 35, 41, 42, 43, 33, 35, 46, 47, 45, 47, 46, 51, 39, 53, 52, 55, 49, 57, 58, 59, 45, 61, 62, 49, 62, 65, 66, 67, 51, 69, 70, 71, 49, 73 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(n)<=n and a(n)=n iff n is squarefree (A005117);

A081211(n)=a(a(n)), see A081212, A081213 and A081214 for iterations until a fix-point is reached.

LINKS

R. Zumkeller, Table of n, a(n) for n = 1..10000

FORMULA

Multiplicative with p^e -> A070321(p^e), p prime.

MATHEMATICA

gsf[n_] := For[k = n, True, k--, If[ SquareFreeQ[k], Return[k]]]; a[n_] := Times @@ gsf /@ Power @@@ FactorInteger[n]; Table[a[n], {n, 1, 80}] (* Jean-François Alcover, Mar 27 2013 *)

CROSSREFS

Sequence in context: A187043 A081211 A081213 * A285719 A070321 A239904

Adjacent sequences:  A081207 A081208 A081209 * A081211 A081212 A081213

KEYWORD

nonn,mult

AUTHOR

Reinhard Zumkeller, Mar 10 2003

STATUS

approved

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Last modified May 28 12:27 EDT 2020. Contains 334681 sequences. (Running on oeis4.)